wsgi: Fixed incorrect parsing of ipv6 addresses in access log

Granian is setting REMOTE_ADDR values using SocketAddr::to_string() which uses
the format <host>:<port> and ipv6 addresses are delimited internally by colons,
so the port that needs to be stripped must be taken from the right and there
must only be one split done to avoid splitting the ipv6 address.

granian/wsgi.py

@@ -80,7 +80,7 @@ def access_log(t, scope, resp_code):
         logger(
             t,
             {
-                'addr_remote': scope['REMOTE_ADDR'].split(':')[0],
+                'addr_remote': scope['REMOTE_ADDR'].rsplit(':', 1)[0],
                 'protocol': scope['SERVER_PROTOCOL'],
                 'path': scope['PATH_INFO'],
                 'qs': scope['QUERY_STRING'],